This invention relates to alloys and especially to dental alloys for casting prostheses and in particular to the well-known nickel-beryllium system.
An example of a nickel-beryllium system of the type including chromium is shown in U.S. Pat. No. 3,704,182. This patent also refers to the use of vanadium. U.S. Pat. No. 3,704,182 is, however, a high beryllium alloy, i.e., 14 plus atomic percent beryllium, which is over 2 weight percent beryllium in the alloy system of his invention and would be over 2 weight percent in the alloy system of the present invention. The casting alloy of U.S. Pat. No. 3,074,182 is an extremely hard alloy which would not be suitable for making dental prostheses.
It has now been discovered that with the use of low beryllium and the amount of vanadium required by the present invention, a dental prostheses alloy is obtained, having substantial uniformity of grain size throughout the entire thickness of the prostheses, both in thin marginal areas and thick pontic areas. In addition, the alloy exhibits exceptional dental porcelain bonding properties and unusual freedom in time-temperature relationships during processing.
It is an object of the present invention to provide a nickel-based casting alloy that exhibits superior dental procelain bonding.
Another object of the present invention is to provide a dental casting alloy that is uniform in grain size throughout its cast mass.
It is a still further object of the present invention to provide a casting alloy suitable for use in forming dental prostheses, using essentially the procedures presently employed in forming such prostheses.
Yet another object of the present invention is the provision of a dental casting alloy, with procelain to metal bonding characteristics that are relatively insensitive to processing variables.